Monday, December 4, 2023

# What Is Frictional Force In Physics

## On What Factors Does The Impact Of Force Depend

Factors affecting Friction | Frictional Force | Physics | Don’t Memorise

The force depends on the direction of the application. If suppose force is applied at an angle then the component of the force will determine the impact of the force on the object. If Force is applied in the opposite direction of intention then it is called a decelerating force.

Force is directly proportional to the mass of an object. The heavier the object the more force is required to move the object. For example, the gravitational pull, which is a force, is directly proportional to the mass of an object. The more the mass, the stronger will be the gravitational pull.

Force is directly proportional to the acceleration of the object. A car at 50 Km/h will have more impact in an accident compared to a similar car moving at 20 Km/h.

## Ways To Reduce Friction

Using lubricants is one way to reduce friction. Lubricants are substances that are put on surfaces to reduce the friction between the surfaces. Some examples of lubricants are motor oil, wax, and grease. Lubricants are usually liquids, but they can be solids or gases. An example of a gas lubricant is the air that comes out of the tiny holes on an air hockey table.

When you work on a bicycle, watch out for the chain! You may get dirty from the grease or oil that keeps the chain moving freely.Without this lubricant, friction between the sections of the chain makes riding difficult.

Friction can also be reduced by switching from sliding kinetic friction to rolling kinetic friction. Ball bearings placed between the wheels and axles of in-line skates and bicycles make the wheels turn more easily by reducing friction. Read more about bearings and how it helps to reduce friction.Another way to reduce the magnitude of friction is to smooth surfaces that rub against each other. For example, rough wood on a park bench can snag your clothes or scratch your skin because there is a large amount of friction between you and the bench. Rubbing the bench with sandpaper makes the bench smoother. As a result, the friction between you and the bench is less. So, the bench will no longer snag your clothes or scratch you. Read about friction coefficient.

## Are There Different Types Of Frictional Force

Yes, there are different types of frictional forces. The friction that takes place between solid surfaces is classified as;Static, Kinetic, Rolling,;and Sliding Friction. The friction that takes place between fluids and gases are termed as fluid friction. Hence, friction is broadly classified as:

• Dry Friction

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## Calculating The Force Of Friction:

Find the Normal Force.

The normal force defines the force that the surface an object is resting on exerts on the object. For a motionless object on a flat surface, the force must exactly resist the force due to gravity, otherwise the object would move, according to Newtons laws of motion. The normal force is the term for the force that does this.

It constantly acts perpendicular to the surface. This means that on a sloppy surface, the normal force would still point straight away from the surface, while the force of gravity would point directly downwards.;

The normal force can be simply defined in most cases by:

N = mg

Here, m denotes the mass of the object, and g represents the acceleration due to gravity, which is 9.8 m/s². This just matches the weight of the object.

For sloppy surfaces, the strength of the normal force is minimizing the more the surface is inclined, so the formula becomes:

N = mg cos

With represent the angle the surface is inclined to.

For a simple case calculation, consider a flat surface with a 2-kg block of wood resting on it. The normal force would point directly upwards , and you would measure:

N = 2 kg × 9.8 N/kg = 19.6 N

Find the Right Coefficient.

The coefficient relies on the object and the specific situation youre working with. If the object is not already moving across the surface, you use that the coefficient of static friction static, but if it is moving you will use the coefficient of sliding friction slide.

F = N

## What Is The Difference Between Static Friction And Kinetic Friction Static Friction Kinetic Friction Static friction is the friction present between two or more objects that are not moving with respect to each other Kinetic friction is the friction present between two or more objects that are in motion with respect to each other. The magnitude of static friction is greater due to the greater value of its coefficient The magnitude of the kinetic friction is comparatively lesser due to the low value of its coefficient The equation representing static friction is given by\ The equation representing kinetic friction is given by\

The video explains the role of friction in walking with the help of animations.

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## What Is Static Friction

Static friction is a force that keeps an object at rest. Static friction definition can be written as:

The friction experienced when individuals try to move a stationary object on a surface, without actually triggering any relative motion between the body and the surface which it is on.

It can be explained as the force of friction which precisely balances the applied force for the duration of the stationary state of the body.

The static frictional force is a self-regulating force, i.e. static friction will at all times be equivalent and opposite to the force applied.R is the reaction force because of the weight W. The external force is F and fr;is the friction. F = -fr;when no motion takes place.

Watch the video to understand the nuances of static friction.

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## Magnitude Of Static Friction

Magnitude of static friction fs is fs;;sN, where s is the coefficient of static friction and N is the magnitude of the normal force.

The symbol means less than or equal to, implying that static friction can have a minimum and a maximum value of sN. Static friction is a responsive force that increases to be equal and opposite to whatever force is exerted, up to its maximum limit. Once the applied force exceeds fs, the object will move. Thus fs = sN.

Once an object is moving, the magnitude of kinetic friction fk is given by fk = kN, where k is the coefficient of kinetic friction. A system in which;fk = kN;is described as a system in which friction behaves simply.

## + Different Types Of Forces

Net Force Physics Problems With Frictional Force and Acceleration

You already know thatForce is nothing but a push or pull on an object.

A force can change the shape, size, speed and direction of an object. A force can even stop a moving object.

Now, what are the different types of forces?

The list is so BIG. As there are so many forces in nature.

Dont worry.

Here, Ill explain the different types of forces in physics with Real Life examples.

Lets get started.

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## What Is The Friction Coefficient

The Friction coefficient is a constant for a pair of surfaces in contact which decides the amount of frictional force generated at the common layer when one surface moves or tends to move with respect to the other surface. This coefficient is presented generally in this way: = F /N= ratio of frictional force and Normal reaction force. It has 2 different sets of values for a pair of surfaces and these are known as 1] the Coefficient of static frictions and 2] the Coefficient of Kinetic frictionk

## What Are The Different Types Of Forces

Based on contact, a force can be classified into:

• Contact force: Muscular force, air resistance, tension, reaction force, and normal force
• Non-contact force: Gravitational force, magnetic force, electrostatic force, and nuclear force

It is possible for a combination of forces to be acting on a body. Like, gravitational force, frictional force, and muscular force can all act together on a body. Let us look at each one of these forces in detail with examples.

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## Numerical Simulation Of The Coulomb Model

Despite being a simplified model of friction, the Coulomb model is useful in many numerical simulation applications such as multibody systems and granular material. Even its most simple expression encapsulates the fundamental effects of sticking and sliding which are required in many applied cases, although specific algorithms have to be designed in order to efficiently numerically integrate mechanical systems with Coulomb friction and bilateral or unilateral contact. Some quite nonlinear effects, such as the so-called , may be encountered with Coulomb friction.

## What Is A Balanced Force A situation of balanced forces is created when forces are acting in the opposite direction with equal magnitude. Example: the normal force and the weight of an object. When the forces acting on a body are balanced then the object will be either in a state of rest or in uniform motion. There will zero acceleration on such an object. You can see examples of balanced forces in our daily lives.

• The normal force and the weight of an object
• When you push a wall. The action-reaction forces are equal and cancel out each other.
• Force applies to an object with a magnitude less than the limiting friction. The frictional force will cancel out the applied force.
• Objects hanging on a wire or string. The tension in the string cancels out the downward force exerted by the hanging object. Hence the object is in a stationary state.

## Problems On Frictional Force:

Problem 1 A 50 N of force is applied to the 6 kg of box. If the coefficient of friction is 0, 3, calculate acceleration of the box?

Solution 1 Fnormal = 60 N 40 N = 20 N

Friction force is ; Ffriction = µ.Fnormal = 0, 3.20N = 6N

Net force in Y to Y = zero,

But, in X + X direction net force is not zero

Fnet = m.a

30 N 6 N = 6 a

a = 4m/s²

Problem 2 – A block of mass M = 10 kg is placed on a surface which is inclined at angle = 45°.;

Mentioning that s = 0.5 is the coefficient of static friction is between block and the surface.

• What will be the minimum force F required to prevent slipping?

• What will be the maximum force F that can be applied without causing the block to slip?;

Solution 2 – The minimum force essential to stop slipping is the minimum force that will inhibit the block from sliding down the incline.

Fmin = 10 g sin – 10 g cos x 0.5.

The maximum force that can be applied without causing the block to slip is the maximum force that can be applied without causing the block to slide up the incline.

Fmax = 10 g sin + 10 g cos x 0.5.

Fmin = 34.65 N, Fmax = 103.94 N

## Cleaning A Mirror With Cloth

Here, a man is cleaning a mirror with cloth.

While cleaning a mirror, mirror and cloth slides against each other. So a friction is produced between them.

This friction produces a force in the opposite direction of cloth.

This type of force is known as the Frictional Force.

There are so many other examples of frictional force that we are experiencing in our daily life.

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Friction considered as a necessary evil has a major disadvantage which includes:

• Wastage of energy such as the heat generated by a machine. Therefore, practically no machine can have 100 percent efficiency.
• Loss of matter such as wearing off the soles of shoes with time while they protect us from slipping or sliding too.

The major advantage includes the easy conversation of one form of energy into another such as when lighting a matchstick or reduction in speedon applying brakes or changing the direction of motion by turning the steering wheel.

## Laws Of Rolling Friction

What is Friction? | Physics | Don’t Memorise

There are three laws of rolling friction:

• With the increase in smoothness, the force of rolling friction decreases.
• Rolling friction is expressed as a product of load and constant to the fractional power.
 F = kLn
• Rolling friction force is directly proportional to load and inversely proportional to the radius of curvature.
 \

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## Laws Of Limiting Friction:

• The direction of limiting frictional force is always contrary to the direction of motion.
• Limiting friction acts tangentially to the two surfaces interacting.
• The magnitude of limiting friction is proportional to the normal reaction amidst the two surfaces.
• The limiting friction hinges upon the material, the nature of the surfaces interacting and their evenness.
• So long as the normal reaction is the same, the magnitude of limiting friction is free of the shape or the area of the surfaces in contact, for any two given surfaces.

Understand the variable and self-adjusting nature of the static friction with the help of the animation provided in the video below.

Put your understanding of this concept to test by answering a few MCQs. Click Start Quiz to begin!

Select the correct answer and click on the Finish buttonCheck your score and answers at the end of the quiz

## Resolution Of Forces In An Inclined Plane

Sometimes forces might act at an angle like in an example of an inclined plane. Then the component of the force acts on the body. In the example above you can see that the component of the weight of the object acts to balance the normal force. Also, the component of weight tries to pull the body down against the action of the kinetic frictional force.

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## Dry Friction And Instabilities

Dry friction can induce several types of instabilities in mechanical systems which display a stable behaviour in the absence of friction.These instabilities may be caused by the decrease of the friction force with an increasing velocity of sliding, by material expansion due to heat generation during friction , or by pure dynamic effects of sliding of two elastic materials . The latter were originally discovered in 1995 by George G. Adams and for smooth surfaces and were later found in periodic rough surfaces. In particular, friction-related dynamical instabilities are thought to be responsible for brake squeal and the ‘song’ of a glass harp, phenomena which involve stick and slip, modelled as a drop of friction coefficient with velocity.

A practically important case is the self-oscillation of the strings of bowed instruments such as the violin, cello, hurdy-gurdy, erhu, etc.

A connection between dry friction and flutter instability in a simple mechanical system has been discovered, watch the movie for more details.

Frictional instabilities can lead to the formation of new self-organized patterns at the sliding interface, such as in-situ formed tribofilms which are utilized for the reduction of friction and wear in so-called self-lubricating materials.

## What Is The Maximum Frictional Force 6
Homework Statement:
The block in the diagram weighs 120N. It will start to slip down the slope when the component of it’s weight acting down the slop equals the maximum frictional force. If the block slips when the angle = 35 degrees what is the maximum frictional force?
Relevant Equations:
Sin*Opposite = Hypotenuse and F=Ma

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## What Does Frictional Force Mean

Frictional force is the opposing force that is created between two surfaces that try to move in the same direction or that try to move in opposite directions. The main purpose of a frictional force is to create resistance to the motion of one surface over the other surface. The frictional force depends on the body surface textures.

## What Is The Line Of Action Of A Force

The line along which a force is acting on an object is called the line of action of the force. The point where the force is acting on an object is called the point of application of the force. The force which opposes the relative motion between the surfaces of two objects in contact and acts along the surfaces is called the force of friction.

Galileo experimentally proved that objects that are in motion move with constant speed when there is no force acting on it. He could note that when a sphere is rolling down an inclined plane, its speed increases because of the gravitational pull which is acting on it.

When all the forces acting on an object are balanced, the net force acting is zero. But, if all the forces acting on a body result in an unbalanced force, then the unbalanced force can accelerate the body, which means that a net force acting on a body can either change the magnitude of its velocity or change the direction of its velocity. For example, when many forces act on a body, and the body is found to be at rest, we can conclude that the net force acting on the body is zero.

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